Hi da Rock,
I can't speak for Rotaryphile but my Terminal Dive calculation assumed 90F and 500 ft for the air density number. Austins about 200 ft above sea level and HOT and I need about 300 feet to pull out. Naturally each data run would have an actual temperature and ground pressure recorded. I use a La Crosse weatherstation thats battery powered.

Me too! I think I'll approach this cautiously. Adding my stuff to a well oiled course syllabus is just adding work for everyone. Then theres the potential damage to the windtunnel from parts abruptly exiting my vehicle. I think I'll initially ask if they might do some low Re plots of some common airfoil sections they probably already have on-hand (in aluminum) and see what happens.

No unmodified Duellist available. I really haven't done a whole lot to the basic plane however except clean it up. I haven't calculated the change in frontal area but I doubt it's reduced more than 2%. My calculations blew me away when I discovered the wing is over 80% of the total.

Frankly, thats much of my motivation behind sharing this stuff. I hope to see more curious people taking the time and spending a little money on advancing the science behind the hobby. It's a lot more satisfying than ARF collecting.

One thing I've noticed upon reading some of these calculations for speed, thrust, weight, and power is that they are neglecting the friction robbing effect of air resistance making their solutions questionable at speeds over 60mph and wildly invalid at speeds anywhere over 100! I've seen several posts mostly on other threads predict speeds based on power at over 200mph without ever considering air resistance. Converting weight/thrust ratios times velocity and other tricks are also invalid.

Ratio's, formulae, and such are often very convenient but designed to only work under a very narrow and specific set of conditions to make the calculations less cumbersome. It gets misused (abused) when someone applies this simplification in a much different context. Other people read this and validate it as reasonable and the error is taken up as a fundamental truth. I hope we can get back to some fundamental physics and quite using tricks.

How are you figuring frontal area? The 80% number is highly unlikely.

From post #12:

"The way I found area for the wing was by finding the largest cross-sectional area of the wing panel perpendicular to the airflow. I found the thickest point of the root rib, added skin thickness and multiplied that number by the length of the panel. I then subtracted a triangular area to compensate for change in thickness from root to tip. "

I thought I made a mistake too so I checked it, THREE times! Heres the dimensions, go for it.
Root max th: 2.1875"
tip max th: 1.4375"
span: 69.0"
wing area: 125in^2
plane total: 155in^2

I have the plane framed up and simply looking at it head on confirms the numbers. It's all wing. The tail feathers are thin sheet, the fuse is a small bullet shape and the nacelles are buried in the wing and small also. It'll be equipped with retracts.

Well, I hate to break the news to you, but the air doesn't care one whit what the frontal area of the wing is. But fear not, it is the most common error in looking at drag. Didn't you read what Banktoturn wrote on the subject in this thread?

You asked how I calculated frontal area implying it should be less than 80%? Thats what I gave you.

Now you say the plane doesn't care about frontal area at all? Common error? What?

BankToTurns comment was a suggestion to use planform area (wing area). Using planform area the percentage of wing area to total area jumps to 96% because of the much larger area involved (and you seemed to have heartburn with 80%!). I was unsure about Banktoturns suggestion of using planform area instead of frontal area so I checked some other sources. It turns out that both frontal and planform are widely used in different instances.

When plotting airfoil polars the coefficient of lift Cl must be calculated using planform area so its convenient when comparing lift to drag on the same plot to use planform area for drag. This is an often cited example.

However, the purpose of my thread is to find parastic drag and the main form of consequence here is the profile drag based on the SHAPE of the entire machine. Since I must use frontal area for the fuselage and nacelles it is more consistent mathematically in this instance to use frontal area for the wing. The only difference will be the magnitude of the drag coefficient Cd of the plane. That, if you had actually understood Banks post, was the thrust of his point.

This is really more explanation than this muddled attack deserved but since it's a grey area I thought it might be interesting.

Any more observations HP? Got any new ratio's for us?

I suggest you do a little bit of research on the subject of drag from wings. Banktoturn did tell you exactly what to do, but expected you would do some of the work. What do you think the Cd of the wing is all about?

Got any new ratio's HP?

For un-accelerated flight, I would expect that the drag from the wing would be in the range of 30% of the total drag.

I was designing the gear and discovered that the landing gear can make 60% of the total drag...looks innocent little gadget but can kill the whole economy of the plane when you don't have enuf power to leave the ground. So watch it.

Towing a drag chute could get a bit complicated, since the drag of a parachute varies quite a bit with shape, but the parachute drag could be calibrated in a relatively small wind tunnel, or perhaps by towing behind a car on a towline long enough to get it out of most of the wind wash generated by the car.

Most university engineering departments have wind tunnels, but they usually have rather small test sections. Only a few of the larger universities commonly have wind tunnels with test sections larger than about two feet square, and they are very costly to operate. I did some engineering work to fix an underperforming wind tunnel recently which had a test section of about three feet square, and consumed about 300 HP to produce about 150 mph wind, generating quite an electric bill in the process.